In the realm of friction modifiers used in passenger car motor oils, there are many options. One of the many options available as an engine oil friction modifier is bis-ethoxy oleylamine which has been used for a number of years as a friction modifier.
Until recently, diesel engine oil formulators focused on the problem of maximizing the useful life of a lubricant and the engine it is used in. This has been done with the aid of wear inhibitors and antioxidants. Formulators had not spent too much time on tuning an engine oil's characteristics in order to maximize fuel economy.
A number of factors have contributed to the recent interest in improving diesel engine fuel economy. Global climate change legislation has slowly but steadily been limiting emissions from diesel engines. In addition, the price of crude oil skyrocketed in 2008. Suddenly fuel costs had superseded labor costs as the single largest expense of many truck fleets. Although the price of crude has dropped off significantly from where it peaked at $145/barrel in 2008, fuel economy is firmly established as an important issue for OEMs, diesel engine owners and diesel engine oil producers.
Addressing fuel economy in heavy duty diesel engines in a manner parallel to that used in passenger car engines has proven to not be the best strategy. Friction modifiers that have been used with success in passenger car engine oils show disappointing results in diesel engines. Reducing friction by reducing the viscosity of the oil has lead to wear issues. Obviously, a new approach is needed to tackle the problem of fuel economy in diesel engines.
New organic friction modifiers (OFMs) designed to function in both passenger car and heavy duty diesel engine oils have begun to emerge. Surprising benefits in friction reduction have been seen with a new class of mixed borate esters of bis-ethoxy alkylamines/amides. These benefits have been demonstrated through both bench and engine testing.
Malec, U.S. Pat. No. 4,231,883 teaches the use of alkoxylated hydrocarbyl amines as friction modifiers.
Chien-Wei et al., U.S. Pat. No. 3,011,880 teaches the use of borate esters of bis alkoxylated hydrocarbyl amides as fuel additives to improve resistance to deposits and low temperature operation.
Colombo, EP393748 teaches the use of borate esters of mono and bis-ethoxylated alkyl amides as friction modifiers and anti corrosion agents in lubricants.
Papay et al., U.S. Pat. No. 4,331,545 teaches the use of borate esters of monoethoxylated hydrocarbyl amides as friction modifiers for both lubricants and fuels. Mixed borate esters with alkyl alcohols and polyhydric alcohols are described.
Horodysky, U.S. Pat. No. 4,382,006 teaches the use of borate esters of bis-ethoxylated alkyl amines as friction modifiers for lubricants. Example borate esters are mixed esters with butanol.
Horodysky, U.S. Pat. No. 4,389,322 teaches the use of borate esters of bis-ethoxylated alkyl amides as friction modifiers for lubricants. Example borate esters are mixed esters with butanol.
Horodysky et al., U.S. Pat. No. 4,406,802 teaches the use of mixed borate esters of compounds including bis-alkoxylated alkyl amines, bis-alkoxylated alkyl amides and alcohol hydroxyesters as friction modifiers in lubricants.
Horodysky et al., U.S. Pat. No. 4,478,732 teaches the use of mixed borate esters of compounds including bis-alkoxylated alkyl amines, bis-alkoxylated alkyl amides and alcohol hydroxyesters as friction modifiers in lubricants.
Yasushi, JP2005320441 teaches the use of a mixed borate ester of bis-ethoxylated alkyl amides and glycerol monoesters in low sulfur formulations as antiwear additives.
None of the lubricants previously described address the problem of friction modification in a diesel engine oil with a mixed borate ester incorporating an hydrocarbyl polyol having at least three hydroxyl groups.